The present invention is related to solid-state electronic heat pumps, known as thermoelectric modules (TEMs), and to their manufacture. More particularly, the present invention is related to an improved manufacturing method so that TEMs can be manufactured at lower cost. The resulting TEM is also improved and can operate at high performance and efficiency.
A thermoelectric module is typically formed by an electrical circuit of elements of alternating types of thermoelectric materials, which are connected in series. Each thermoelectric material element has two sides, one side connected to a higher voltage than the other side, when the module is in operation. Physically the thermoelectric material elements are arranged so that the hot sides of thermoelectric material elements define one side of the TEM and the cold sides of the elements define the other side of the TEM.
Operationally, as current is driven through the TEM, the electronic carriers in the thermoelectric material elements carry thermal energy from one direction to the other. In other words, the TEM is a heat pump which transfers heat by electric current. There are no moving parts, as in the case of a mechanical heat pump.
Present TEM manufacturing methods require skilled technicians to arrange the thermoelectric material elements during manufacture. To replace this manual assembly, other methods have been attempted, including automation, robots, and mechanical spacing aids, without much success.
Besides high manufacturing costs, a problem with these conventionally manufactured TEMs has been that the operating point of maximum cooling power is substantially different from the operating point of maximum coefficient of performance. That is, at maximum cooling, the TEM does not operate at peak efficiency. The result is that, for a particular application which limits the number of TEMs, a large, expensive power supply is required to drive the TEMs at high power and low efficiency. Alternatively, where the constraint on the number of TEMs is removed, a less expensive power supply can drive an increased number of TEMs at lower power and higher efficiency. Neither alternative is satisfactory. In one case, increased costs go toward the power supply. In the other case, the increased costs go toward the additional TEMs, which occupy more space.
Efforts to overcome this problem appear to be directed toward the development of new thermoelectric materials which have higher maximums in cooling power or coefficient of performance. In contrast, a TEM manufactured with present thermoelectric materials increases its cooling power so that a much greater cooling power according to the present invention is reached around the maximum coefficient of performance. As new thermoelectric materials are developed, a TEM with the improved performance according to the present invention should also be correspondingly improved.
The present invention permits for a superior arrangement of such elements without skilled technicians.